We dyno'd the 408 when it was built. Everything fine. Brought it home, installed damper, input shaft bushing and new clutch w/ new flywheel bolts. Now that the motor is painted & in the car, I can't turn the crank by hand OR with starter.

I have gone as far as to disconnect 4 speed trans with the thought that shaft was in a bind, but it still won't turn.

Could it be that I installed the damper incorrectly or damaged something?? Could it be something with the flywheel bolts (too long?)?I was trying to set it to TDC so I could fire it up for the first time, and somehow the car ended up in pieces and my day went to hell.

This motor isn't budging at all. What is stopping my crank from turning?!?

A bolt too long holding the flywheel, to the back of the crankshaft?
Can you turn it any direction?

It won't turn either direction.

What damper was on the engine when it was on the dyno? Is the flywheel/clutch/pressure plate all new? Any chance the flywheel binds in the bellhousing? How about the bolts mounting the crank pulley?

Flywheel to crank bolts are too long is the most probable cause.

Sheldon

Remove the flywheel first, then the damper...

the balancer can't really hold it, so I'd bet on flywheel bolts also. There is not alot of extra room there.

Make sure that the crank pulley bolts aren't too long and hitting the timing cover at the front seal.

I way going through my timing covers looking for one to clean up when I saw one the looked like the crank pulley bolts were tightened in to it (that or puller bolts were twisted into it).

Definitely check the flywheel bolts.

Typically the starter or a socket & breaker bar would cause long bolts attaching the pulley to chew up the timing cover but the engine would still turn & start/run..... So i agree probably the flywheel bolts are to long... You should be able to see that fairly well with the clutch cover removed you can see the crank flange & the rear main bearing/seal retainer cap...

Well, I can see the flange/bolts with the inspection cover removed and it doesn't seem the bolts are too long. They just barely make it through the flange.

The crank pulley bolts are short, so that can't be it either. Again, the trans is unbolted and pulled back to where the splines are not in the clutch anymore and this has been isolated to the motor. I don't want to pull the trans out, because it will require the removal of my AAR exhaust (pain in the butt), as well as the driveshaft loop, which is bolted to the body of the car.... just a bunch of reinstall headaches which seem unnecessary.

I can't really remember clearly, its been so long, but I may have removed the damper for painting... Would it be possible for me to have overtightened the damper to the point where it could be causing this? Long shot, but what about the distributor gear? Could I have jammed that with a careless install? If so, would it jam the motor up like this?

Other than that, I don't see what could possibly be causing this. It is REALLY stuck!

The damper shouldn't be able to lock the engine... Well the part that goes through the cover & the bolt going into the crank shouldn't... If anything is contacting the damper outside the cover it's possible.... Good luck, this sucks..

OK, perhaps this is a long shot, but is it possible the pressure plate cover is against the bell housing? Taller, installed before the bell?
I did this once long ago, but on something else...using a non stock set up...?

Pull the spark plugs...

When I was stabbing the 4 speed while the motor was on a dolly, about to go into the car.... I tapped the end of the trans a few times with a 2.5 lb hammer. It was stuck with about a half inch left and I couldn't wrestle it in anymore (thought it was just a tight new bushing).

Could that have damaged a bearing in the motor??

If you damaged the pilot bushing-bearing, it would still let engine turn. An engine thrust bearing is a tough piece that should not be your problem. When you say it won't budge, do you mean it is locked tight in either direction?